Coupled 3-D thermo-hydro-mechanical analysis of geotechnological in situ tests

Abstract

The present work discusses the numerical modelling of thermo-hydro-mechanical coupled processes for two in situ experiments on engineered barrier systems, which were performed at a real test site in the geological underground. Based on the phase related balance equations for mass, linear momentum and energy, a classical continuum approach for multiphysics analyses in porous media is presented. Within this context, the non-isothermal Richards' approximation is used for flow simulations in a partially saturated deformable solid skeleton. Regarding the constitutive modelling, basically relations typically discussed in literature for the applications under consideration are applied, and are calibrated on experimental data. Some specific problem-related modifications are presented. An incremental staggered finite element scheme is preferred to solve the coupled nonlinear initial-boundary value problem. Due to the process complexity of the combined simulation of both of the in situ experiments, a 3-D model is required. Additionally, the realisation of parallel algorithms in conjunction with high performance computing facilities essentially improves the efficiency of the numerical simulations. The presented models and algorithms are implemented into the scientific finite element code OpenGeoSys. Based on the analysis of the in situ experiments under consideration, the capabilities of OpenGeoSys to model application-oriented problems are shown.